Vickers-Armstrong made the first M. 31 75 mm AA gun in 1920. Even though it incorporated many modern features the British Army initially refused it. However, it had more success abroad, where it was bought by Belgium, Lithuania, Holland, Portugal, Turkey and China.

In 1935 it was selected to be the new standard heavy AA gun of the Romanian Army. The contract, which was signed in 1936, was for 25 batteries (150 pieces), of which 8 batteries were going to be built by Vickers and the rest of 17 under license by the Resita Works.

In March 1939, the British firm delivered the 48 guns and the first battery made at Resita equipped a Romanian AA artillery regiment by 1 August the same year. To hurry the production, after WWII erupted in Europe, a second production line was established at the Astra Works in Brasov. As the war progressed, the Romanian factories ignored the license contract and continued to produce the AA guns the army badly needed.

The initial 25 batteries also included a fire control system, built by Vickers, but which was already outdated at the beginning of the war. It was replaced by a Romanian system created by major Bungescu, which permitted the coordination of multiple batteries and obtained better results.

The Vickers/Resita model 1936/39 75mm AA gun was used by almost all ten Romanian AA regiments, throughout the war, and was much appreciated for its qualities in the anti-aircraft and also anti-tank role (as it was used in some desperate situations at Stalingrad). It remained in service until the early 50s, when it was replaced by Soviet built models.